Abstract: Fraction of absorbed photosynthetically active radiation (FPAR), the part of photosynthetically active radiation that is absorbed by vegetation, is one of the important parameters in terrestrial ecosystem simulating models. The purpose of this study was to clarify spatial-temporal changes of the FPAR in Qinling-Daba Mountains where is on the important north-south climate transitional zone in China. Based on the MODIS remote sensing data and climate datasets from 2006 to 2015, a linear regression analysis was used to examine spatial-temporal changes of FPAR at pixel scale in Qinling-Daba Mountains. A correlation analysis was conducted to analyze the relationship between vegetation FPAR and climate factors. The results showed that there was spatial difference in FPAR distribution in the Qinling-Daba Mountains, with high FPAR values in the center and southeast and lower values in the northwest and northeast of study area. They decreased with altitude, with obvious vertical zonality along mountains. From 2006 to 2015, the FPAR increased in the central region and decreased in the surrounding area. The areas with significantly increased FPAR values were mainly distributed in the basins of Jialing River and Danjiang River and the downstream of Hanjiang River. The FPAR values slightly decreased in parts of the Gannan Plateau and the Western Sichuan Plateau. During last decade, the FPAR of vegetation, on the whole, appeared a significantly increasing trend with a rate of 4.8%·10 a^-1 (P<0.05) and the most outstanding vegetation was crop (P<0.05). Among the four seasons, the FPAR significantly increased in winter (P<0.05). Annually, the correlation between vegetation FPAR and climate factors showed that vegetation FPAR was more correlated with mean annual temperature than that with mean annual precipitation on all vegetation types. However, the correlations differed among vegetation types. Coniferous forest and broad-leaved forest FPAR had higher correlations with mean annual temperature than other types, while grasslands and croplands were influenced much more by mean annual precipitation than by mean annual temperature.

Key words: biological filtrationvegetable floatingbed combined system, vegetable floating-bed system, greenhouse turtle breeding wastewater, nitrogen and phosphorus removal.